Welcome to my blog. Astronomy is a fantastic hobby. I started off with just a passing interest, but now it's never far from my mind. My earliest posts were all about observations, but now, I write about all sorts of astronomy related topics. Please feel free to comment, or subscribe to receive an email when I add a new post. Enjoy, and thanks for reading.

Tuesday, 15 September 2015

Final processed images from Cornwall

Good evening reader, and thanks for taking the time to stop by and browse. It's been a few days since I returned from holidays in Cornwall and the experience of some good quality clear skies.
I've had the chance to look through the photographic data that I collected while there, and run it through some processing. I've dabbled with Deep Sky Stacker and GIMP before, but nothing serious at all. I felt that I now had some data worth spending a bit more time working with.
I split my photography into 4 different sets. Each set using slightly different settings on the camera. In the grand scheme of things, I haven't collected a huge amount of data per set, but all in all, a total of around 11 minutes of exposure per picture which has given me enough to work with.
My camera is an unmodded Cannon EOS 1100d with standard twin lens kit. All stacking was done in Deep Sky Stacker 3.3.4 and some light processing in GIMP 2. Both these pieces of software are free, opensource available to download for Windows and Linux.

Set 1.

Set 1 was the first run I did with the iOptron Sky Tracker. I must admit, I wasn't really concentrating on the picture taking, more what was going on with the equipment. So, it was no surprise when reviewing the data that the images were slightly out of focus. For this set, I just pointed the camera up into the milky way somewhere. Again, not concentrating on any particular target.

Set 1 comprised of 18 frames of 30 second exposures shot at f/4.5 ISO-800 at a focal length of 18mm. I also took 5 offset/bias frames and 5 darks, Though out of focus, there is some very good definition of the dust lanes coming through from the spiral arms of the Milky Way.

Set 2.

With a bit more confidence in the process, I moved onto the second set. Sticking with 18 frames at 30 seconds, this time, I changed the other camera settings to F/5, ISO-1600 and twisted the lens to a focal length of 46mm. I used 5 bias frames and 4 dark frames. I also changed the position of the camera pointing it vaguely into the constellation of Andromeda. The result being that you can now see the galaxy of Andromeda beginning to emerge against the background of other stars.

Set 3.

I was starting to struggle with dew appearing on the lens of the camera. This is going to prove to be more of a problem when trying exposures measuring many minutes each during the course of a few hours at a time. I decided to change the lens to the 300mm lens that came with the camera and continue with the trial.

I left the camera pointing to the same area of sky, and chose to amend more of the camera settings. This has allowed be to build up a comparison of similar pictures in similar circumstances, but using different settings. It will help me decide what to use in the future for better results.

This time, I used 19 frames (must have lost count somewhere!) and 5 bias and 5 dark frames. I worked at a focal length of 80mm, f/4.5, ISO-1600. This time, the finished product has a better dark background which helps show off the stars and the galaxy.

Set 4.

Finally, I decided to try picking out Andromeda in more details. Achieving focus when doing this type of photography is quite time consuming, and so having a laptop with remote shooting abilities on hand allows me to take a series of photos, zoom in on the photo straight away and make any focus adjustments required. To do this, I left most of the camera settings alone, but cranked up the ISO setting to as high as it could go on my camera. In this case, this was ISO-6400. Once I had achieved the best focus I could in the conditions, I prepared the camera for the final set of pictures.

Set 4 consists of 18 frames with 5 bias frames and 5 darks. The settings on the camera were changed to f/5.6, ISO-6400 and the lens set to a maximum focal length of 300mm. The final product is quite please for a first attempt at astrophotography at this focal length. During processing, I could see through the curves that there is plenty of data there to be worked with. However, I need to hone my processing skills to bring the data out visually in to the final photo.

This picture shows the core of M31, the Andromeda Galaxy quite nicely. The extended galaxy is also visible as a lighter surrounding to the core. This is made up of stars, gas and dust all being held within the gravitational pull of Andromeda. Also visible is the 2nd galaxy of the pair, M32. In this picture it can be seen just below and to the right of the main core of Andromeda. Its a pale orange in colour and could be mistaken for a slightly larger star when compared to the others in the vicinity. And finally, directly above the core of Andromeda, another galaxy designated M110. Again, pale orange in colour, the core can be picked out, along with the outer edges of the galaxy.

These 4 photos represent one evening of photography in excellent conditions, then followed by several evenings of stacking and learning on the hoof basic processing skills to get them this far. As I develop my processing and photography skills, I'll post more results. I've already got a few targets in mind, and with winter approaching, there are others that will keep me occupied through the start of next year. Hopefully, I'll have chance to attempt a couple of clusters in Hercules, and possibly some larger nebulas too.